1. Field of the Invention
The present invention relates to an apparatus for elevator group control used to operate a plurality of elevator cars between a plurality of floors.
2. Description of the Related Art
Recently, in order to improve an operation efficiency of a plurality of parallel elevator cars and to improve service quality for elevator passengers, a microcomputer has been used to systematically and rapidly allocate elevator cars for responding to hall calls on each floor.
When a hall call is generated, an apparatus for group control performs the following control.
1) Control for selecting and allocating, from a plurality of elevator cars, an optimal elevator car for performing service for the hall call.
2) Control for inhibiting other elevator cars except for the allocated elevator car to respond to the hall call.
In the above case, at an elevator hall, an allocation indication lamp arranged near an entrance of the allocated elevator car is turned on, and a chime rings and the indication lamp is flickered immediately before arrival of the elevator car.
In the elevator system as described above, along with recent development of microcomputers, measurement of, such as elevator car call registration data and getting on/off load data is performed in a real-time manner in response to each elevator hall to monitor a traffic flow between the floors.
In addition, the above apparatus for group control predicts a traffic demand from generation of a hall call in accordance with the traffic flow and allocates an optimal elevator car on the basis of the prediction.
In a building where a restaurant is located on a particular floor, a traffic demand for the particular floor is significantly increased during a particular time period such as the first half of a lunch break. Therefore, the particular time period in which the traffic demand is increased requires a transportation efficiency higher than that in an ordinary time period.
The high transportation efficiency is defined by the following conditions:
(1) Service quality is equalized between floors,
(2) An elevator car is full or almost full upon arrival at a particular floor,
(3) An elevator car heading for a particular floor does not pass floors, allocated to the elevator car and generating hall calls, because the elevator car is full before it arrives at the particular floor.
A conventional apparatus for elevator group control employs the following means in order to ensure a high transportation efficiency. When elevator cars to hall calls on respective floors are allocated, a load on each floor at which an elevator car is to be stopped is predicted along with the predicted nonresponse time. Control is performed in accordance with the prediction such that an allocated elevator car does not pass a floor, at which the elevator car is to be stopped, because it is full. That is, the control is basically performed to allocate elevator cars such that passengers get on operating elevator cars as equally as possible.
As described above, when hall calls are generated from individual floors, elevator cars are allocated by predicting passengers who are to get on from the corresponding halls. However, for peak hours when a traffic demand to a particular floor is significantly increased, the following problems arise because the number of waiting passengers per call is large.
For example, assume that, as shown in FIG. 1, calls are generated on two floors f.sub.1 and f.sub.2, a predicted load on each floor is 16 passengers, and an elevator car loading capacity is 24 passengers. If an elevator car No. 3 is allocated to the floor f.sub.1 and an elevator car No. 1 or 2 is allocated to the floor f.sub.2 a predicted response time for the floor f.sub.2 is long. Therefore, the elevator car No. 3 arrives at a restaurant floor with 16 passengers, resulting in low transportation efficiency. For this reason, the floor f.sub.2 may be allocated to the elevator car No. 3 by relative evaluation. Assume that the number of waiting passengers on each of the floors f.sub.1 and f.sub.2 coincides with the prediction, i.e., 16, when the elevator car No. 3 is allocated to the floors f.sub.1 and f.sub.2. In this case, although 16 passengers can get on the elevator car on the floor f.sub.1, only eight passengers can get on the elevator car on the floor f.sub.2. This is not preferred in terms of equalization in service quality between floors.
As described above, even when allocation is performed in consideration of prediction of loads, if the number of waiting passengers is large on each floor, a floor farther from a particular floor is advantageous while that closer to the particular floor is disadvantageous unless the number of passengers in each elevator car is limited. However, although equalization is realized by limiting the number of passengers as described above, it is actually difficult to limit the number of passengers when use convenience of passengers is taken into consideration.
As a patent application related to this application, there is U.S. Pat. No. 5,168,135 to Kubo et al.